Radiation-cured, laminated flexible packaging material and radiation-curable, adhesive composition

ABSTRACT

Provided are laminated flexible packaging materials ( 20 ) suitable for containing a pharmaceutical, food or beverage grade product. The laminated flexible packaging material includes a layer of flexible packaging material ( 26 ) bound to at least one other layer of flexible packaging material ( 22 ) by a radiation-cured laminating adhesive composition ( 24 ) formulated from a radiation-curable laminating adhesive containing at least 50% of one or more radiation-curable, carboxylic acid functional monomers and 0.1 to 20% of an organic titanate compound. Also provided is a radiation-curable laminating adhesive containing at least 50% of one or more radiation-curable, carboxylic acid functional monomers and 0.1 to 20% of an organic titanate compound.

[0001] This application is a Continuation-in-Part Application of U.S.Ser. No. 10/253,810, filed on Sep. 25, 2002, which is a DivisionalApplication of U.S. Ser. No. 09/348,662, filed on Jul. 6, 1999, now U.S.Pat. No. 6,472,056, the complete disclosures of which are incorporatedherein by reference. This application also claims priority to U.S.serial No. 60/349,429, filed on Jan. 22, 2002, the complete disclosureof which is incorporated herein by reference.

1. FIELD OF THE INVENTION

[0002] The invention relates to a radiation-cured, laminated flexiblepackaging material. The invention also relates to a radiation-curableadhesive composition suitable for use in forming the laminated flexiblepackaging material.

2. BACKGROUND OF THE INVENTION

[0003] Flexible packaging is widely used for food, non-food, andpharmaceutical applications. Flexible packaging uses a wide range ofdifferent types of materials including various types of plastic films,paper, and aluminum foil. The plastic films include various types ofpolyolefins, polyesters, and polyamides. The films may be variouscombinations of homopolymers, copolymers, and polymer blends. The filmsmay be a single layer or may be coextruded in multiple layers. The filmsare also commonly coated, metalized, or otherwise treated to enhance theperformance of the resulting package. Packaging materials are selectedbased on a variety of factors including desired barrier properties,appearance, cost, physical feel, printability, sealing properties, easyopen features, and reclosing features.

[0004] Two main classes of flexible packaging materials are: 1) mono-webpackaging, which includes a mono-web of a coextruded film; and 2)laminated packaging. Laminate packaging is often desired due to the factthat it is advantageous to combine two or more webs in order two obtainthe desired properties of the resulting package. Reasons for usinglaminated packaging constructions include: 1) to contain the graphicsbetween layers in order to provide protection and enhanced appearance;2) to maintain product freshness by taking advantage of the barrierproperties of the individual layers; 3) to combine a heat stable web forprinting with a heat sealable web for sealing the package; 4) to providedesired feel and handling properties to maximize consumer appeal; 5) toenhance the package strength in order to maintain integrity for filling,shipping, and consumer handling. Several different technologies are usedto bond the layers used in laminated packaging. Two classes oflaminating technology are extrusion lamination and adhesive lamination.Extrusion lamination involves melting and depositing a layer of thermalplastic resin such as polyethylene between two webs of packagingmaterials. The different types of adhesives currently used to laminateflexible packing materials include: 1) one component solvent base; 2)two component solvent base; 3) one component water base; 4) twocomponent water base; and 5) two component solventless.

[0005] Solvent base adhesives have inherent limitations that include: 1)emission of volatile organic compounds (VOCs); 2) high cost of solventincineration or recovery equipment; 3) flammability; and 4) analysis andcontrol of residual solvents in the package.

[0006] Water base adhesives have inherent limitations that include: 1)the need for extended drying equipment; 2) the effect of heat used indrying on thermally sensitive packaging films; 3) variable drying ratesdependant on ambient humidity levels; and 4) difficulty in starting andstopping due to adhesive drying on the application equipment.

[0007] Any two component system (solvent base, water base, orsolventless) has inherent disadvantages that include: 1) the need foraccurate mixing of the two components; 2) limited pot life of the mixedcomponents; and 3) the time delay (typically 2 to 5 days) required forthe two components to react to achieve the final adhesive properties.Other limitations associated with two component solventless adhesivesinclude: 1) the need for heated application equipment; and 2) residualtoxic aromatic amines, which are byproducts of isocyanate based curingsystems.

[0008] Radiation-curable adhesives can potentially offer numerousadvantages over these other flexible packaging laminating adhesives.They may offer: 1) stable one-part compositions; 2) little or no VOCs;and 3) full adhesive performance immediately upon cure. UV curablelaminating adhesives require at least one layer of packing material thatis sufficiently transparent to allow penetration of UV light to cure theadhesive. EB curing has the added advantage of being able to penetrateopaque or printed packaging materials in order to cure the adhesive.

[0009] The main challenge in the development of radiation-curablelaminating adhesives are: 1) two provide bonding and chemical resistancethat is adequate for desired packaging application; and 2) have lowodor, taint, and migration to allow packaging of food and pharmaceuticalproducts.

[0010] Radiation-curable materials such as inks and coatings aregenerally based on relatively low molecular weight reactive monomers andoligomers. The components are designed to be converted to high molecularweight polymers upon UV or EB irradiation. High conversions of the lowmolecular weight components can be achieved; however, some residualamount of monomer or oligomers normally remains. These residualcomponents can be responsible for odor, taint, and migration issues inthe packaging. The art of radiation-curable inks and coatings does notaddress the same problems associated with flexible laminate packagingmaterials, and, thus, one skilled in the art would not be motivated tolook to the art of radiation-curable inks and coatings when addressingthe problems associated with radiation-curable adhesives for use inlaminates.

[0011] A discussion of the issues associated with the use ofradiation-curable materials in food packaging applications may be foundin PCT Application number WO 02/081576 (Chatterjee), which isincorporated herein by reference. The compositions disclosed byChatterjee contain water, which is displaced from the ink or coatingupon radiation-curing. This cannot be done with a laminating adhesivesince the water would be trapped between two layers of packagingmaterials and, thus, Chatterjee is not helpful in addressing theproblems associated with radiation-curable adhesives for use in makinglaminates.

[0012] In radiation-curable laminating adhesives, the residual lowmolecular weight components are initially found within the curedadhesive, which is located between two layers of packaging materials.Some types of packaging materials, such as aluminum foil, are goodbarrier materials and are effective for preventing migration of lowmolecular weight components in to the food or pharmaceutical product.Other packaging materials, such as polyolefin based materials, are knownto be less effective barriers to migration of low molecular weightorganic compounds. Thus, there is a need for a radiation-curableadhesive material that when suitably cured exhibits substantiallyreduced migration through layers in a laminated flexible packagingmaterial.

[0013] Flexible packaging materials also have problems with delaminationof the layers during normal use, especially when the package containsaggressive liquids or certain aggressive food products. Delamination canalso be an issue during processing or the package. This can include theaddition of closures, filling, sealing, and heat processing. Thus, thereis a need for a radiation-curable adhesive material that when suitablycured exhibits sufficient adhesion to prevent delamination of the layersduring normal use.

SUMMARY OF THE INVENTION

[0014] An objective of the invention is to provide radiation-cured,laminated flexible packaging materials, which do not leach residualradiation-curable monomers into the contents thereof and exhibitsufficient adhesion to avoid delamination of the layers during normaluse.

[0015] Another objective is to provide radiation-curable laminatingadhesives that can be used to form laminated flexible packagingmaterials which do not leach radiation-curable monomers into thecontents thereof and exhibit sufficient adhesion to avoid delaminationof the layers during normal use.

[0016] The above objective and other objectives are surprisinglyobtained by using a radiation-curable laminating adhesive formulatedfrom carboxylic acid functional monomers and organic titanate compounds.

[0017] The invention provides a novel laminated flexible packagingmaterial suitable for containing a pharmaceutical or food grade productcomprising at least two layers of flexible packaging materials bondedtogether by a radiation-cured laminating adhesive, wherein theradiation-curable laminating adhesive comprises at least 50% of one ormore carboxylic acid functional (meth)acrylate monomers which are thehalf-ester formed by the reaction of a hydroxy(meth)acrylate compoundwith an organic anhydride, and about 0.1 to about 20% of at least oneselected from the group consisting of organic titanates, organiczirconates, organic aluminates, and organic zinc. Organic titanates andorganic zirconates are preferred, with organic titanates being mostpreferred.

[0018] The invention also provides a novel radiation-curable laminatingadhesive comprising at least 50% by weight of one or more carboxylicacid functional (meth)acrylate monomers which are the half-ester formedby the reaction of a hydroxy(meth)acrylate compound with an organicanhydride, and 0.1 to 20% by weight of at least one selected from thegroup consisting of organic titanates, organic zirconates, organicaluminates, and organic zinc. Organic titanates and organic zirconatesare preferred, with organic titanates being most preferred.

[0019] The present invention also relates to products packaged in theflexible packaging material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 illustrates a side, cross-sectional view of aradiation-cured, laminated flexible packaging material;

[0021]FIG. 2 illustrates a side, cross-sectional view of aradiation-cured, laminated flexible packaging material;

[0022]FIG. 3 illustrates a side, cross-sectional view of aradiation-cured, laminated flexible packaging material;

[0023]FIG. 4 illustrates a side view of a radiation lamination process;and

[0024]FIG. 5 illustrates a side, cross-sectional view of a packagedproduct.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0025] Radiation-Curable Laminating Adhesive

[0026] The radiation-curable laminating adhesive (hereinafter referredto as “radiation-curable adhesive composition”) comprises at least 50wt. % of one or more carboxylic acid functional, radiation-curablemonomers (hereinafter referred to as “carboxylic acid functionalmonomer”). Preferably, the radiation-curable adhesive compositioncomprises at least 80 wt. % of one or more carboxylic acid functionalmonomers, and more preferably at least 90 wt. % of one or morecarboxylic acid functional monomers. All wt. % are based on the totalweight of the radiation-curable composition unless stated otherwiseherein. While the radiation-curable composition may contain conventionalnon-carboxylic acid functional monomers if desired, preferablysubstantially all of the radiation-curable monomers present in theradiation-curable adhesive comprise at least one carboxylic acidfunctional group.

[0027] Preferably, the carboxylic acid functional monomers are selectedsuch that when a radiation-cured laminate is formed using theradiation-curable adhesive, the laminate exhibits less than 50 ppbextraction of uncured monomer. As shown in Example 5, one skilled in theart will easily be able to select carboxylic acid functional monomer(s)to provide a suitable extraction value for a desired flexible packagingmaterial.

[0028] The carboxylic acid functional monomer preferably has a numberaverage molecular weight of from about 100 to about 3000, morepreferably from about 150 to about 2000, and most preferably from about200 to about 1500. The simplest type of carboxylic acid functionalmonomer is acrylic acid. However, acrylic acid is not desirable becauseof odor, toxicity and low molecular weight. Therefore, preferredradiation-curable adhesive compositions are substantially free ofacrylic acid.

[0029] One skilled in the art will easily be able to form the desiredcarboxylic acid functional monomer based on well known reactionmechanisms. For example, using the well known reaction between ahydroxyl functional group and an anhydride, a compound containing both ahydroxyl functional group and a desired radiation-curable functionalgroup can be reacted with an anhydride compound to form the desiredcarboxylic functional monomer. Suitable anhydrides include, but are notlimited to: phthalic anhydride; maleic anhydride; trimellitic anhydride;tetrahydrophthalic anhydride; hexahydrophthalic anhydride;tetrachlorophthalic anhydride; adipic anhydride; azelaic anhydride;sebacic anhydride; succinic anhydride; glutaric anhydride; malonicanhydride; pimelic anhydride; suberic anhydride; 2,2-dimethylsuccinicanhydride; 3,3-dimethylglutaric anhydride; 2,2-dimethylglutaricanhydride; dodecenylsuccinic anhydride; nadic methyl anhydride; octenylsuccinic anhydride, HET anhydride; and the like.

[0030] The compound containing a hydroxyl functional group and aradiation-curable functional group (“hydroxy functional,radiation-curable compound”) can contain any desired radiation-curablefunctional group suitable for the desired application. Theradiation-curable functional group preferably comprises ethylenicunsaturation. Examples of suitable ethylenic unsaturation includeacrylate, methacrylate, styrene, vinylether, vinyl ester, N-substitutedacrylamide, vinyl amide, maleate esters or fumarate esters. Preferably,the ethylenic unsaturation is provided by an acrylate or methacrylategroup. Use of the term “(meth)acrylate” refers to either acrylate ormethacrylate, or mixtures thereof.

[0031] Examples of suitable hydroxy functional, radiation-curablecompounds containing (meth)acrylate groups include the following, butare not limited thereto: 2-hydroxyethyl (meth)acrylate; 2-hydroxypropyl(meth)acrylate; 2-hydroxybutyl (meth)acrylate; 2-hydroxy3-phenyloxypropyl (meth)acrylate; 1,4-butanediol mono(meth)acrylate;4-hydroxycyclohexyl (meth)acrylate; 1,6-hexanediol mono(meth)acrylate;neopentylglycol mono(meth)acrylate; trimethylolpropane di(meth)acrylate;trimethylolethane di(meth)acrylate; pentaerythritol tri(meth)acrylate;dipentaerythritol penta(meth)acrylate; and

[0032] hydroxy functional (meth)acrylates represented by the followingformula,

[0033] wherein R₁ is a hydrogen atom or a methyl group and n is aninteger from 1 to 5. Commercially available examples include the hydroxyterminated (meth)acrylate prepolymers sold as “Tone” prepolymers (DowChemical). The (meth)acrylate compounds can be used either alone or inadmixture of two or more of them. Among these (meth)acrylate compounds,2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate areespecially preferred. Examples of hydroxy functional, radiation-curablecompounds having vinyl ether functional groups include, for example,4-hydroxybutyl vinyl ether, and triethylene glycol monovinyl ether.

[0034] Preferably, the radiation-curable functional group is acrylate ormethacrylate, with acrylate being the most preferred.

[0035] A particularly preferred carboxylic acid functional monomer isthe product of the reaction of 2-hydroxyethylacrylate (HEA) withsuccinic anhydride, as shown in the following formula:

[0036] If desired, the carboxylic acid functional monomer can also beformed by reacting a suitable dicarboxylic acid functional compound witha hydroxy functional, radiation-curable compound. However, this methodis not preferred since water is formed during the reaction of thehydroxyl group with a carboxylic acid group, which water must be removedprior to use of the carboxylic monomer in the radiation-curable adhesivecomposition.

[0037] Carboxylic acid functional monomers and oligomers can also beformed by various combinations of polyanhydrides and/or polyols, asdesired.

[0038] While not preferred, oligomeric forms of acrylic acid can also beused as the carboxylic acid functional monomer, which can be formed, forexample, by dimerizing or trimerizing acrylic acid by well known selfaddition reactions. A stable dimer compound is betacarboxyethylacrylate(“BCEA”). However, BCEA is not preferred since it usually containsresidual amounts of acrylic acid.

[0039] One skilled the art will easily be able to formulate theradiation-curable adhesive composition to provide a suitable viscosityfor the desired application. Usually, the viscosity of theradiation-curable adhesive composition should be low, for example about3000 centipoise or less, at the application temperature, to facilitateapplication to the substrate. Usually, the application temperature isroom temperature (25° C.). However, higher application temperatures canbe utilized as desired. The carboxylic acid functional monomerpreferably has a low viscosity, in order to avoid the use of diluentmonomers, to provide a viscosity that is suitable for application of theradiation-curable adhesive to a layer of flexible packaging material.Suitable viscosities of the carboxylic functional monomer include fromabout 50 to about 10,000 centipoise at the application temperature, morepreferably from about 100 to about 5000 centipoise at the applicationtemperature.

[0040] It has also been found that certain combinations of carboxylicacid functional monomers are advantageous because of their enhancedbonding characteristics and reduced migration properties. In particular,monomers formed from the reaction of hydroxyl acrylates and alkenesubstituted succinic anhydrides or phthalic anhydride are useful informulations to improve the water resistance of the finished laminate.The monomers may be used in various ratios. The preferred ratio willdepend on the specific materials that are being bonded, as shown inExample 5. One skilled in the art will easily be able to select suitablecombinations of carboxylic acid functional monomers to provide thedesired migration and adhesion properties for the selected layer offlexible packaging material based on the disclosure provided herein,without undue experimentation.

[0041] When the radiation-curable adhesive is formulated for curing byexposure to visible light, ultraviolet light, or the like, one or morephotoinitiators and/or photosensitizers can be used as polymerizationinitiators to enhance the cure speed. Examples of suitablephotoinitiators and photosensitizers include but are not limited to:2,2′-(2,5-thiophenediyl)bis(5-tert-butybenzoxazole); 1-hydroxycyclohexylphenyl ketone; 2,2-dimethoxy-2-phenylacetophenone; xanthone; fluorenone;anthraquinone; 3-methylacetophenone; 4-chlorobenzophenone;4,4′-dimethoxybenzophenone; 4,4′-diaminobenzophenone; Michier's ketone;benzophenone; benzoin propyl ether; benzoin ethyl ether; benzyl dimethylketal, 1-(4-isopropylphenyl)-2hydroxy-2-methylpropane-1-one;2-hydroxy-2-methyl-1phenylpropane-1one; methylbenzoyl formatethioxanthone; diethylthioxanthone; 2-isopropylthioxanthone;2-chlorothioxanthone;2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropane-1-one; and2,4,6-trimethylbenzoyidiphenylphosphine oxide. Commercially availableexamples include IRGACURE 184, 369, 500, 651, 819, 907, and 2959, andDarocur 1173 (Ciba Geigy); Lucirin TPO (BASF); and Ebecryl P36 and P37(UCB Co.).

[0042] Preferably, polymeric photoinitiators are utilized in theradiation-curable adhesive composition. The use of polymericphotoinitiators further reduces the possibility of photoinitiator orfragments of the photoinitiator migrating. Examples of suitablepolymeric photoinitiators include, but are not limited to, thecommercially available KIP 100, KIP 150 and Esacure KK (Lamberti).

[0043] If desired, one or more photoinitiators and/or photosensitizerscan be incorporated in the radiation-curable adhesive coatingcomposition in an amount of about 0.1 to about 10% by weight of thetotal composition.

[0044] If the radiation-curable adhesive composition is formulated toutilize a free-radical curing system by exposure to an electron beam, aphotoinitiator is generally not beneficial. However, in cationicallycured systems, a photoinitiator is beneficial even when performing anelectron beam cure. Based on the disclosure provided herein, one skilledin the art of formulating radiation-curable adhesive compositions willeasily be able formulate a suitable curing system for the desiredapplication, without undue experimentation.

[0045] The radiation-curable adhesives can also containradiation-curable oligomers. Migration is generally not a concern witholigomers due to their higher molecular weight relative to the molecularweight of monomers. (Meth)acrylate functional oligomers are preferred.These include but are not limited to epoxy(meth)acrylates,urethane(meth)acrylates, polyester(meth)acrylate oligomers,(meth)acrylated acrylic oligomers, and (meth)acrylated oligomers basedon copolymers of maleic anhydride, such as those sold under thetradename of Sarbox (Sartomer).

[0046] The adhesive compositions can be formulated to provide improvedbond strengths and improved water resistance properties when suitablycured in laminated structures by incorporating one or more organictitanate compounds. While many different titanate compounds may be used,certain titanates are preferred due to their stability in the presenceof carboxylic acid functional monomers. Certain titanates also providesuperior bonding characteristics. Useful levels of titanate compoundsare from about 0.1 to about 20% by weight, preferably from about 1 toabout 15% by weight, based on the total weight of the composition.

[0047] Organic titanates are a well-known class of chemical compounds.The two major classes of organic titanates are tretraalkyl titanates andtitanate chelates. Teraalkyl titanates have the general structureTi(OR)₄, where R is the residue of an organic alcohol such as isopropylalcohol, n-butanol, 2-ethyl hexyl acohol, etc. The organic portion oftitanate chelates have more than one active sight that may becoordinated to the titanium. Examples of the organic portion of atitanate chelate include triethanol amine, acetoacetonate, and ethylacetoacetate. A discussion of organic titanates is a available in aGeneral Brochure for Tyzor trade name products available from DuPont.

[0048] Organic titanates have several known commercial uses. Theseinclude catalysts for esterification reactions, surface modification oforganic and inorganic materials, reagents for creation of gel-sols, andcross-linkers for polymers. The use of organic titanates inradiation-curable laminating adhesive compositions according to thepresent invention are heretofore unknown.

[0049] The present invention relates to the incorporation of organictitanate compounds in radiation-curable laminating adhesives forpackaging applications. In particular it has been found to beadvantageous to incorporate organic titanate compounds based oncarboxylic acid functional monomers. The primary advantage of theorganic titanate compounds is to provide enhanced bonding along withmoisture and chemical resistance in the laminated packaging materials.

[0050] A commercial example of an organic titanate incorporating acarboxylic acid functional monomer is KR 39DS from KenrichPetrochemicals. This organic titanate has three acrylic acid groups andone dietyhyleneglycol monomethyl ether group. However, when thistitanate is incorporated into an adhesive formulation containingadditional carboxylic acid functional monomer, the acid group willequilibrate releasing free acrylic acid. Acrylic acid is not desired dueto problems with odor, toxicity, and low molecular weight, and should beavoided.

[0051] We have found that it is advantageous to use organic titanatecompounds based carboxylic acid functional monomers that aresubstantially free of acrylic acid. These include carboxylic acidfunctional monomers described earlier which are the reaction products ofhydroxy functional (meth)acrylate compounds with organic anhydrides.

[0052] Desired organic titanate compounds may be formed by the reactionof the carboxylic functional monomers with alkyl titanates. Thisinvolves the displacement and evaporation of the corresponding alkylalcohol. For example, the half-ester of 2-hydroxyethylacrylate andsuccinic anhydride may be reacted with tetraisopropyl titanate. Thisreaction is driven by the evaporation of isopropyl alcohol. In somecases it may be desirable to use organic titanates that have bothchelate groups and alkyl groups. An example is bis-triethanol aminediisporopyl titanate. In this case, one would expect that only theisopropyl alcohol groups would be displaced by the carboxylic acidmonomers.

[0053] These compounds formed by the reaction hydroxy(meth)acrylate-anhydride half esters with alkyl titanates are novelmaterials.

[0054] The new carboxylic acid monomer titanate compounds may beprepared and isolated as shown in Example 1. Alternatively, thesecompounds may be formed in-situ by incorporating the desired organictitanate in the adhesive formulation containing carboxylic acidfunctional monomers as shown in Examples 3 through 7. Generally, forfood applications it is not desirable to have the liberated alkylalcohol present in the adhesive. In these cases, the alcohol may beevaporated from the mixture by heating, mixing, sparging, or processingthe mixture at reduced pressure.

[0055] In place of the organic titanate, it is believed that organiczirconates, organic aluminates, and/or organic zinc, may also provideimproved adhesion properties in the present adhesive compositions.However, organic titanates and organic zirconates are preferred, withorganic titanates being most preferred.

[0056] The radiation-curable adhesive can also include additives such asfillers, flow additives, anti-foaming additives, pigments, dyes, orresinous materials dispersed or solubilized in the composition. Theselection and use of such additives is within the skill of the art.

[0057] When suitably cured, the carboxylic acid functional monomers usedin the present invention have been found to provide the unexpectedcombination of sufficient adhesion to low surface energy layers, such aspolyolefin protective films, to avoid delamination and substantiallyavoid migrating through the layers the in the uncured free-monomer form.

[0058] The radiation-curable adhesive composition can also be used toform improved laminated flexible packaging materials, as describedbelow.

[0059] Laminated Flexible Packaging Material

[0060] The formation of laminated flexible packaging materials iswell-known and therefore will not be discussed in detail herein. Thenovel laminated flexible packaging materials described herein can beeasily produced using conventional techniques and replacing conventionallaminating adhesives with the radiation-curable laminating adhesivesdescribed herein. Preferred methods of applying the radiation-curableadhesive includes use of well-known web coating methods such as rollcoating, gravure, offset gravure, etc. The adhesive may be applied andcured in-line with the printing or off-line in a separate laminatingstep as desired.

[0061] When using low surface energy layers, such as polyolefins,preferably the surface of the layer to be bonded has beensurface-treated to enhance adhesion. Surface treating is well known andany conventional surface treating method can be used as desired for theparticular application. Examples of suitable surface treating methodsinclude corona treatments, chemical treatments, plasma and flametreatments. Preferably, when a polyolefin based layer is utilized acorona treatment or flame treatment is first applied to the surfaceprior to bonding with a radiation-curable adhesive.

[0062] The laminated flexible packaging material will be described withreference to FIGS. 1-3. As shown in FIGS. 1-3, the laminated flexiblepackaging material 20 includes at least one second layer of flexiblepackaging material 22 laminated to a first layer of flexible packagingmaterial 26 by the novel radiation-cured, adhesive 24, where layer 26 isthe layer that will be on the inside of the finished package. Thelaminated flexible packaging material 20 can also include other layersas desired. Examples of suitable materials for the at least one secondlayer 22 and first layer 26 include, but are not limited to: paper,aluminum foil, metalized films, coated films, printed films, co-extrudedfilms, polyester films, polyolefin based films, white polyolefin basedfilms, polyamide based films, copolymer films, and films containingvarious polymer blends. Preferably, the first layer 26 is polyolefinbased.

[0063] The radiation-curable laminating adhesive described herein can beused to provide an improved laminated flexible packaging material inwhich the problem of contamination from migrating monomers issubstantially reduced. It has been found that the carboxylic acidmonomers of the radiation-curable adhesive composition migrate throughlayers of the flexible packaging materials, especially polyolefins, insignificantly less amounts than monomers used in conventionalradiation-curable adhesives. It has also been found that the carboxylicacid monomers used in the present invention provide sufficient adhesionto many types of packaging materials when suitably cured to avoiddelamination of the laminated flexible packaging material during use.

[0064] The radiation-curable, adhesive composition described herein canbe applied and cured using conventional techniques, such as by UV lightfrom medium pressure mercury lamps directly through the layers. Whenusing ultra-violet (UV) light to cure the radiation-curable adhesivecomposition, a polymeric material should be selected which does notprevent or substantially inhibit curing of the radiation-curableadhesive by absorbing or shielding the UV light. Thus, at least one ofthe second layer 22 or the first layer 26 is preferably substantiallyclear when UV curing is desired. A substantially clear layer 22 can beformed from any suitable material. Examples of suitable substantiallyclear polymeric materials include polyolefins, polyesters andpolystyrenes. Preferably, the layer 22 is formed from a polyolefin.

[0065] Alternatively, electron beam radiation (EB) may be used to curethe radiation-curable adhesive composition. The layer 22 and the layer26 do not need to be substantially clear when EB curing is utilized.

[0066] Examples of suitable polyolefins for use in a preferred layer 26and/or when polyolefin is used in the layer 22 include, but are notlimited to, homopolymers or copolymers of ethylene, butylene, propylene,hexene, octene, etc. Preferred polyolefin based films includepolypropylene and polyethylene, such as high-density polyethylene (HDPE)or linear-low-density polyethylene (LLDPE), polyiosbutylene (PIB).Oriented forms of polypropylene can be used as desired, such asbiaxially oriented (BOPP) or oriented polypropylene (OPP).

[0067] If desired, the polyolefin for use in layer 22 or 26 may becoated, blended, copolymerized or coextruded with other materials toenhance the barrier, handling, appearance or sealing properties. Thesemodifications are included in the definitions of “polyolefin based” and“comprising polyolefin” for the layers 22 or 26. Common coatings includepolyvinylidene chloride (PVdC), acrylic based coatings, and variousother barrier and-heat-seal coatings. The polyolefin may also receive athin layer of metal using a vacuum metalization process. Commonpolyolefin copolymers used to produce films for flexible packaginginclude copolymers of ethylene and vinlyacetate (EVA), and ethylene andvinyl alcohol (EVOH), ethylene and acrylic acid, ethylene and ethylacrylate. In spite of the fact that many of these modifications areknown to improve the barrier properties of polyolefins, a migratingresistant laminating adhesive is still desirable to prevent off-flavorand odor in the packaged product.

[0068] U.S. Pat. No. 5,399,396 discloses further examples of suitablelayers for use in the laminated flexible packaging material, which areincorporated herein by reference. Other suitable layers are described inDiane Twede and Ron Goddard, “Packaging Materials,” 2^(nd) Edition, PiraInternational, Surry, UK 1998.

[0069] Another example of a laminated flexible packaging material isshown in FIG. 2, which includes a clear layer 26 comprising a polyolefinwhich has been reverse printed 28 on inside surface thereof and thenbonded to a layer 22 using the radiation-curable, adhesive composition24. In this type package, the printed material would be readable on theinside surface of the package.

[0070] As shown in FIG. 3, another example of laminated flexiblepackaging material includes a clear layer 22 which has been reverseprinted 28 on inside surface thereof and then bonded to a layer 26 usingthe radiation-curable, adhesive composition 24. In this type of package,the printed material would be readable on the outside of the package.

[0071] While not shown in the drawings, a further example of a laminatedflexible packaging material includes a clear layer bonded to a whitepolyolefin layer having printed material on an outside surface thereofbonded together using the radiation-curable, adhesive composition. Theprinting can be performed using any conventional method, such aswell-known ink and/or electrophotographic techniques. Preferred methodsinclude the use of a flexographic or gravure printing press to applyprint in a continuous line.

[0072] The layer 22, layer 26 and adhesive layer 24 can be constructedat any thickness as desired for the particular application. For example,the layer 22 is usually about 0.1 to about 5 mils thick, preferablyabout 0.3 to about 3 mils thick. The adhesive layer 24 is usually about0.03 to about 1 mil thick, preferably about 0.05 to about 0.2 milsthick. The layer 26 is usually about 0.1 to about 5 mils thick.

[0073] The laminated flexible packaging material can be formed by usingany conventional process. FIG. 4 illustrates an example of a radiationlamination process for making a 2-layer flexible laminate packagingmaterial, and an optional 3-layer flexible laminate packaging material.Any number of layers can be bonded together using the presentradiation-curable adhesive.

[0074] A first layer of flexible packaging material 101 is unwound. Thefirst layer 101 may be fed from a roll or directly from a printing pressused to apply graphics to the packaging. An adhesive coating 103 isapplied to the layer 101 using the coating application roller 102 toform and adhesive coating layer 104. This is a simplified drawing. Manydifferent types of roll coating methods may be used including methodswith up to about 6 rollers. The adhesive reservoir holding the adhesivecoating 103 may be open or closed. Liquid adhesive may also be pumpedfrom a feed system. The adhesive application system including theadhesive 103 and roller(s) 102 may be at be at ambient temperature, orheated facilitate achieving the desired application weight and flowproperties.

[0075] A second layer of flexible packaging material 105 is unwound andapplied to the adhesive coating layer 104 using the nip rollers 106 toform a 2-layer laminate 107. The nip rollers 106 can be made of variousdifferent materials including, for example, rubber, steel, and ceramic.Roll pressure can be set for best performance and appearance. Therollers 106 may be at ambient temperature or heated.

[0076] An optional second laminating adhesive application roller 108 canbe used to apply a second adhesive coating 109 to form an adhesivecoating 110 on the laminate 107. The optional third layer of flexiblepackaging material 111 is unwound and applied to the adhesive coating110 using the optional second set of laminating nip rollers 112 to forma 3-layer laminate 113.

[0077] Electron beam generating unit or UV lamp unit 114 then appliesaccelerated electrons or UV radiation to the laminate 113 to cure atleast one of the adhesive coatings 104 and/or 110. If UV is used, thelayer(s) of flexible packaging materials must allow at least partialtransmission of UV light to cure the adhesive(s). Opaque or printedmaterials may be used with EB since accelerated electrons can penetratethrough layers of opaque packaging materials. EB accelerating potentialshould be at least high enough to penetrate the layers of packagingmaterials to cure the adhesives. The equipment should be shielded toprevent worker exposure to the UV light or secondary x-rays which areassociated with EB generation. An optional back-up roller or beam dump116 may be chilled to control excess heat from the curing process.

[0078] Commercial electron beam generating units are available frommultiple suppliers including Energy Sciences Inc., (ESI) and AdvancedElectron Beams (AEB). The penetration of the electrons into thepackaging material is determined by the acceleration potential of thebeam. Generally a range of potentials from about 60 to 250 KV isappropriate for most flexible packaging laminations. A range of about 70to 170 KV is preferred. The total electron beam energy (dose) applied tothe material is measured in units of Mrads. A range of dosages fromabout 0.5 to 6.0 Mrads is appropriate for curing the adhesives of thepresent invention. A dosage range of about 1.0 to 4.0 Mrads ispreferred.

[0079] The cured laminate 117 can be forwarded to an optional post-cureweb processing, which usually includes trimming, slitting, and/orsheeting. The cured laminate 117 can be rewound to form a roll 119 forlaminated web of packaging material.

[0080] Preferably, both adhesives 104 and 110 are radiation-curableadhesives according to the present invention. However, one of theadhesives may be non-radiation-curable if desired. In multiple layerlaminates, at least one adhesive layer must comprise a radiation-curableadhesive according to the present invention. Radiation-curable adhesivesmust be applied before the curing unit 114. Non-radiation-curableadhesives may be applied before or after the curing unit 114. This is asimplified drawing for illustration purposes. Other web treating,cleaning, handling, and coating accessories are typically part or theprocess.

[0081] The immediate EB or UV cure allows fast in-line processing.However, with other types of laminating adhesives, it is difficult toprocess in-line since the adhesive may not be adequately cured in ashort time period.

[0082] The improved laminated flexible packaging material can be used tocontain beverages, pharmaceuticals, medical and dental devices, and foodproducts. Preferred examples are snack food packaging, dry food mixes,meat packaging, cheese packaging, and flavored beverage containers. Itmay also be desirable to use the improved laminated flexible packagingfor non-food industrial or consumer packaging. Although taste or andmigration may not be a concern for non-food applications, the immediatebonding and resistance to delamination achieved with these newradiation-curable laminating adhesives may be desired. Examples ofindustrial and consumer non-food applications includes packaging wet anddry wipe products.

[0083] The packages can be formed using any conventional process. FIG. 5illustrates a cross-sectional view of a packaged material 120 containedwithin the flexible packaging material 122. The edges 124 of theflexible packaging material 122 can be sealed using any conventionalsealing method, such as heat sealing or cold sealing using adhesives, asdesired.

[0084] The invention will now be further described with reference to thefollowing non-limiting Examples and Comparative Examples. The migrationof the carboxylic acid functional monomers of the radiation-curable,adhesive composition have been tested using food industry standards. Thetest results clearly demonstrate that the carboxylic acid functionalmonomers migrate through layers of a laminated flexible packagingmaterial to a significantly less degree than monomers utilized inconventional radiation-curable adhesives. Thus, the improvedradiation-curable, adhesive composition is capable of providing anadhesive layer which substantially reduces the risk of uncured monomersmigrating through flexible packaging layers and contaminating thecontents of a packaged product with uncured monomer.

[0085] The test results also demonstrate that when the presentradiation-curable adhesives are suitably cured they exhibit improvedadhesion and resistance to delamination, especially when liquids arepresent.

[0086] The new and improved adhesive compositions according to thepresent invention are illustrated by the following examples:

EXAMPLE 1

[0087] A UV/EB curable titanate compound was prepared by reacting 4.4molar equivalents of the carboxylic acid functional monomer which is thehalf-ester of 2-hydroxy ethyl acrylate (HEA) and succinic anhydride(HEA-succinate monomer) with 1.0 molar equivalents of titaniumtetraisoproxide. Isopropyl alcohol was removed by heating the mixtureunder a vacuum. The resulting product was a high viscosity clear reddishliquid. A titanium content of 4.8% was determined gravimetrically asTiO₂ by heating to a dry ash. This is in excellent agreement with theexpected 4.8% theoretical titanium content demonstrating that theproduct is a new titanate compound incorporating 4 moles HEA-succinateper mole of titanium.

EXAMPLE 2

[0088] The organic titanate compound from Example 1 was used in theadhesive formulations shown in Table 1. For comparison the “A” formuladid not contain titanate. Thin films of each adhesive (approximate 0.1mil) were applied to various layers of flexible packaging materials. Asecond layer of flexible packaging material was laid onto the wetadhesives and the resulting laminates were cured by EB irradiation at165 kV with a dosage of 3.0 Mrads. The bond strength of the resultinglaminates was determined using tensile testing equipment in a T-peelconfiguration at a speed of 12 inches/min. The results are shown in theTable below. The results show increased bond strength for theoPP/metalized oPP laminates in the presence of the titanate compound.The results also show that the titanate improves the water resistancefor the two polyester (PET) film laminations. TABLE 1 A B C AdhesiveFormula (wt %) HEA-succinate 99.8 94.8 89.8 Titanate From Example 1 5.010.0 Fluorosurfactant 0.2 0.2 0.2 Average Peel Strength (g/in)oPP/metalized oPP 210 Film Tear Film Tear PET/LLDPE (dry) Film Tear FilmTear Film Tear PET/LLDPE (1 hr water) 174 181 237 PET/Al foil (dry) FilmTear Film Tear Film Tear PET/Al foil (1 hr water) 46 68 102

EXAMPLE 3

[0089] A series of titanate compounds were incorporated into UV curablelaminating adhesives as shown in Table 2. The adhesives were applied ata thickness of approximately 0.2 mils to a polypropylene film. A secondlayer of polypropylene film was placed over the wet adhesives. Theadhesives were then cured by UV exposure through the top film with a 300w/in medium pressure mercury arc lamp at a conveyor speed of 100 ft/minto form laminates. The bond strengths of the laminates were determinedby a T-peel test. The results show a significant increase in theadhesive strength in the presence of all of the titanate compounds. Thestability was checked upon storage for one month at room temperature.The mixture containing the triethanol amine titanate remained liquidwith no precipitation (ppt) and no noticeable change in viscosity. TABLE2 Adhesive Formula (parts by wt) A B C D E HEA-succinate 95 95 95 95 95Lucerin TPO, BASF 3 3 3 3 3 Titanium acetyl acetonate 5 Octylene glycoltitanate 5 Triethanol amine titanate 5 Tetra 2-ethyihexyl titanate 5Average peel strength (g/in) 136 191 172 191 159 Solution stability, onemonth clear ppt. ppt. clear ppt.

EXAMPLE 4

[0090] An experimental design was conducted to evaluate adhesivecompositions containing up to 4.0 percent triethanol amine titanate, upto 10 percent of difunctional monomer, which is the reaction product ofone equivalent of benzophenone dianhydride with two equivalents of anhydroxy acrylate based on caprolactone (Tone M-100), and up to 15percent of a difunctional aromatic urethane acrylate oligomer (SartomerCN973). The balance of the formula was composed of HEA-succinatemonomer. The test formulations were coated onto a web of inner packaginglayer using an offset gravure coater. The adhesive weight was controlledto 1.2±0.2 pounds/3000 ft2. A web of outer packaging material was nippedto the wet adhesive. The laminates were then cured by exposing themoving web to an electron beam at 165 kV at a dosage of 3.0 Mrads. Thebond strengths of the laminates was measured by T-peel testing. Theoptimum adhesive formulations obtained from the analysis of the T-peeldata are shown in Table 3. The results show the benefits of the titanatecompound in the adhesive formulas. TABLE 3 Outer Layer Material oPP OPPPET Inner Layer Material oPP Metalized oPP LLDPE HEA-succinate (wt %) 9896 77.31 Urethane acrylate (wt %) 0 0 8.69 Difunctional monomer (wt %) 00 10 Triethanol amine titanate (wt %) 2 4 4 Maximum Peel Strength (g/in)315 277 273 Average Peel Strength (g/in) 231 249 226

EXAMPLE 5

[0091] An experimental design was conducted to evaluate adhesivecompositions containing three different monomers, which are half estersof 2-hydroxyethyl acrylate (HEA) with acid anhydrides. The threeanhydrides were succinic anhydride, phthalic anhydride, and 2-dodecenylsuccinic anhydride (DSA). The compositions contained at least 20%HEA-succinate, up to 80 percent HEA-phthalate, up to 80 percent HEA-DSA,and up to 8% triethanol amine titanate. All compositions also contained0.2% of a fluorosurfactant. The adhesives were coated and cured asdescribed in Example 4. The water resistance of the laminates wasmeasured by conducting T-peel testing immediately after 1 hour immersionof a one inch wide strip in water. The optimum adhesive formulationsobtained from the analysis of the T-peel data are shown in Table 4. TheT-peel results for a 96% HEA-succinate, 4% triethanol amine titanateformulation are also shown for comparison. The results show theadvantage of having the HEA-phthalate and HEA-dodecenyl succinatemonomers in the formulations in order to achieve improved waterresistance. TABLE 4 Outer Layer oPP oPP OPP OPP PET PET PET PET MaterialInner Layer Material oPP oPP Met. Met. LLDPE LLDPE Al foil Al oPP oPPfoil HEA-succinate (wt 20.27 96 89.65 96 20.0 96 20.17 96 %)HEA-phthalate (wt 0 0 0 0 53.1 0 0.60 0 %) HEA-dodecenyl 79.73 0 2.35 018.9 0 71.53 0 succinate (wt %) Triethanolamine 0 4 8.0 4 8.0 4 7.7 4titanate (wt %) Peel Strength After 175 140 193 184 346 246 273 152Water Soak (g/in)

EXAMPLE 6

[0092] An adhesive formulation was prepared comprising 94.9 wt %HEA-succinate, 4% trethanol amine titanate, and 0.1% fluorosurfactant.The adhesive was coated onto a web of coextruded packaging film based onethylene vinyl alcohol copolymer (EVOH) and linear low densitypolyethylene (LLDPE). A web of polyester (PET) packaging film was nippedto the wet adhesive and the adhesive was cured by exposing the movingweb through the PET side using a 110 KV electron beam at a dosage of 3.0Mrads to form laminates. The laminates were extracted from the LLDPEside using Miglyol 812 at 66° C. for 2 hours followed by 40° C. for 238hours. This protocol is recognized by the FDA as a method to testsuitability for of packaging materials for food applications. The testswere run in triplicate and validated with appropriate controls at anindependent laboratory. No adhesive components were detected in theextracts with detection limits of 50 PPB.

EXAMPLE 7

[0093] Five adhesive formulations were prepared as shown in Table 5. Theadhesives were used to bond two layers of 0.7 mil oriented polypropylene(oPP) film. The adhesives were applied and EB cured using the proceduredescribed in Example 4. Any attempts to separate the films resulted inimmediate tearing of the oPP films. This illustrates the excellentbonding of the adhesives. The laminated films were mounted in singleside test cell, which contained 10 milliliters of 95% ethanol for each1.0 square inch of laminated area. The laminates were extracted for 10days at 40° C. This is a test protocol recognized by FDA to determinethe suitability of packaging materials for use in food applications. Theextraction results for three of the adhesive components are shown inTable 5. The important points illustrated by this example are: 1) Theimportance high levels carboxylic acid monomers in order to achieve lowextraction levels (A, B, C have 91.8% total carboxylic acid monomercompared to 59.8% for D and 39.8% for E); 2) The benefit using multiplecarboxylic acid functional monomers in the formulation (compare theextraction results for A vs. B and C); and 3) The high level oftrimethylol propane triacrylate (TMPTA) monomer extracted relative tothe much lower extraction of the carboxylic acid functional acrylatemonomers (HEA-succinate and HEA-phthalate). TMPTA is a trifunctionalmonomer while the carboxylic acid functional monomers in this exampleare monofunctional. One skilled in the art would expect lower extractionwith multifunctional materials. Thus, the lower extraction carboxylicacid functional monomers is surprising and unexpected. TABLE 5 AdhesiveFormula (wt %) A B C D E HEA-succinate 56.8 31.8 20.0 39.8 19.8HEA-phthalate 30.0 35.9 20.0 20.0 HEA-dodecenyl succinate 35.0 30.0 35.9TMPTA 40.0 60 Fluorosurfactant 0.2 0.2 0.2 0.2 0.2 Triethanolaminetitanate 8.0 8.0 8.0 Extraction results (PPB) HEA-succinate 88 39 48 63147 HEA-phthalate 8.0 10.5 22.5 42 TMPTA 480 1155

EXAMPLE 8

[0094] An organic zirconate compound based on HEA-succinate monomer wasprepared by Dupont under the experimental designation TLF-9566. Thisorganic zirconate was used in the adhesive formulations shown in Table6. For comparison the “A” formula did not contain the zirconate. Thinfilms of each adhesive (approximate 0.1 mil) were applied to variouslayers of flexible packaging materials. A second layer of flexiblepackaging material was laid onto the wet adhesives and the resultinglaminates were cured by EB irradiation at 165 KV with a dosage of 3.0Mrads. The bond strength of the resulting laminates was determined in aT-peel test. The results are shown in Table 6 below. The results showincreased bond strength for the oPP/metalized oPP laminates in thepresence of the zirconate compound. The results also show that thezirconate improves the water resistance for the two polyester (PET) filmlaminations. TABLE 6 A B C Adhesive Formula (wt %) HEA-succinate 99.894.8 89.8 Organic Zirconate TLF-9566 5.0 10.0 Fluorosurfactant 0.2 0.20.2 Average Peel Strength (g/in) oPP/metalized oPP 210 Film Tear FilmTear PET/LLDPE (dry) Film Tear Film Tear Film Tear PET/LLDPE (1 hrwater) 174 Film Tear Film Tear PET/Al foil (dry) Film Tear Film TearFilm Tear PET/Al foil (1 hr water) 46 93 49

[0095] The test results demonstrate that the improved radiation-curableadhesive composition is capable of providing an adhesive layer havingimproved adhesive properties and which substantially reduces the risk ofuncured monomers migrating through a packaging material layer andcontaminating the contents of a packaged product with uncured monomer.

[0096] While the claimed invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to one ofordinary skill in the art that various changes and modifications can bemade to the claimed invention without departing from the spirit andscope thereof.

1. A radiation-curable laminating adhesive comprising: a) at least 50%by weight of one or more carboxylic acid functional (meth)acrylatemonomers which are the half-ester formed by the reaction of ahydroxy(meth)acrylate compound with an organic anhydride, and b) 0.1 to20% by weight of an organic titanate compound.
 2. The radiation-curablelaminating adhesive of claim 1, wherein said anhydride is selected fromthe group consisting of phthalic anhydride; maleic anhydride;trimellitic anhydride; tetrahydrophthalic anhydride; hexahydrophthalicanhydride; tetrachlorophthalic anhydride; adipic anhydride; azelaicanhydride; sebacic anhydride; succinic anhydride; glutaric anhydride;malonic anhydride; pimelic anhydride; suberic anhydride;2,2-dimethylsuccinic anhydride; 3,3-dimethylglutaric anhydride;2,2-dimethylglutaric anhydride; dodecenylsuccinic anhydride; nadicmethyl anhydride; and HET anhydride and said hydroxy (meth)acrylatecompound is selected from the group consisting of 2-hydroxyethyl(meth)acrylate; 2-hydroxypropyl (meth)acrylate; 2-hydroxybutyl(meth)acrylate; 2-hydroxy 3-phenyloxypropyl (meth)acrylate;1,4-butanediol mono(meth)acrylate; 4-hydroxycyclohexyl (meth)acrylate;1,6-hexanediol mono(meth)acrylate; neopentylglycol mono(meth)acrylate;trimethylolpropane di(meth)acrylate; trimethylolethane di(meth)acrylate;pentaerythritol tri(meth)acrylate; dipentaerythritolpenta(meth)acrylate; octenyl succinic anhydride, and hydroxy functional(meth)acrylates represented by the following formula,

wherein R₁ is a hydrogen atom or a methyl group and n is an integer from1 to
 5. 3. The radiation-curable laminating adhesive of claim 1, whereinsaid anhydride is succinic anhydride.
 4. The radiation-curablelaminating adhesive of claim 1, wherein said anhydride is phthalicanhydride.
 5. The radiation-curable laminating adhesive of claim 1,wherein said anhydride is alkene substituted succinic anhydride.
 6. Theradiation-curable laminating adhesive of claim 5, wherein said anhydrideis dodecenyl anhydride.
 7. The radiation-curable laminating adhesive ofclaim 5, wherein said anhydride is octenyl succinic anhydride.
 8. Theradiation-curable laminating adhesive of claim 1, wherein said hydroxy(meth)acrylate compound is 2-hydroxyethyl acrylate.
 9. Theradiation-curable laminating adhesive of claim 1, wherein said hydroxy(meth)acrylate compound is 2-hydroxyethyl methacrylate.
 10. Theradiation-curable laminating adhesive of claim 1, wherein the organictitanate comprises the reaction product of a least one titanate havingone to four alkyl groups and at least one half-ester compound formed bythe reaction of a hydroxy (meth)acrylate compound with an organicanhydride.
 11. The radiation-curable laminating adhesive of claim 10,wherein the organic titanate is formed by pre-reacting the alkyltitanate with the half-ester compound that is formed by the reaction ofa hydroxy (meth)acrylate compound with an organic anhydride.
 12. Theradiation-curable laminating adhesive of claim 10, wherein the organictitanate is formed in-situ with blending of other laminating adhesivecomponents.
 13. The radiation-curable laminating adhesive of claim 1,wherein the organic titanate is formed from tetraisopropyl titanate. 14.The radiation-curable laminating adhesive of claim 1, wherein theorganic titanate is formed from triethanol amine titanate.
 15. Theradiation-curable laminating adhesive of claim 1, wherein the organictitanate is present at a level of about 1 to about 15% by weight of theadhesive composition.
 16. The radiation-curable laminating adhesive ofclaim 1, further comprising less than 50% by weight of at least one monoor multi-functional (meth)acrylate monomer or oligomer.
 17. Theradiation-curable laminating adhesive of claim 1, wherein the adhesiveis formulated to be curable by electron beam radiation through at leastone layer of a laminated structure.
 18. The radiation-curable laminatingadhesive of claim 1, further comprising about 0.2 to about 15% of aphotoinitiator, wherein the adhesive is curable by ultravioletradiation.
 19. The radiation-curable laminating adhesive of claim 18,wherein the photoinitiator comprises a polymeric material.
 20. Aradiation-curable laminating adhesive according to claim 1, furthercomprising at least one photoinitiator.
 21. A radiation-curablelaminating adhesive according to claim 1, wherein the adhesivecomposition is substantially free of acrylic acid.
 22. Aradiation-curable laminating adhesive according to claim 1, furthercomprising at least one photosensitizer.
 23. A radiation-curablelaminating adhesive according to claim 1, comprising at least 80% ofsaid one or more radiation-curable, carboxylic acid functional monomers.24. A radiation-curable laminating adhesive according to claim 1,comprising at least 90% of said one or more radiation-curable,carboxylic acid functional monomers.
 25. A radiation-curable laminatingadhesive according to claim 1, wherein said radiation-curable laminatingadhesive is substantially free of non-carboxylic acid functionalmonomers.
 26. A radiation-curable laminating adhesive according to claim1, wherein said radiation-curable, carboxylic acid functional monomercomprises an acrylate functional group.
 27. A radiation-curablelaminating adhesive according to claim 1, wherein saidradiation-curable, carboxylic acid functional monomer comprises amethacrylate functional group.
 28. A radiation-curable laminatingadhesive according to claim 1, wherein said carboxylic acid monomer hasa number average molecular weight of from about 100 to about
 3000. 29. Aradiation-curable laminating adhesive according to claim 1, wherein saidcarboxylic acid monomer has a number average molecular weight of fromabout 150 to about
 2000. 30. A radiation-curable laminating adhesiveaccording to claim 1, wherein said carboxylic acid monomer has a numberaverage molecular weight of from about 200 to about
 1500. 31. Aradiation-curable laminating adhesive according to claim 1, wherein saidcomposition has a viscosity of about 10,000 centipoise or less at anapplication temperature.
 32. A radiation-curable laminating adhesiveaccording to claim 1, wherein said carboxylic functional monomer has aviscosity of about 50 to about 10,000 centipoise at an applicationtemperature.
 33. A radiation-curable laminating adhesive according toclaim 1, wherein said carboxylic functional monomer has a viscosity ofabout 100 to about 5,000 centipoise at an application temperature.
 34. Aradiation-curable laminating adhesive suitable for packagingpharmaceutical or food grade products comprising: a. at least 50% of oneor more carboxylic acid functional (meth)acrylate monomers which are thehalf-ester formed by the reaction of a hydroxy(meth)acrylate compoundwith an organic anhydride, and b. about 0.1 to about 20% of an organictitanate compound, characterized in that the carboxylic acid functionalmonomer(s) are selected such that when the adhesive is suitably cured toform a laminated package the cured adhesive allows less than 50 PPBextraction into the contents of the laminated package.
 35. A laminatedflexible package material comprising at least two layers of flexiblepackaging materials bonded together by a radiation-cured laminatingadhesive, wherein the radiation-curable laminating adhesive comprises:a. at least 50% of one or more carboxylic acid functional (meth)acrylatemonomers which are the half-ester formed by the reaction of ahydroxy(meth)acrylate compound with an organic anhydride, and b. about0.1 to about 20% of an organic titanate compound.
 36. The laminatedflexible packaging material of claim 35, wherein said anhydrideanhydride is selected from the group consisting of phthalic anhydride;maleic anhydride; trimellitic anhydride; tetrahydrophthalic anhydride;hexahydrophthalic anhydride; tetrachlorophthalic anhydride; adipicanhydride; azelaic anhydride; sebacic anhydride; succinic anhydride;glutaric anhydride; malonic anhydride; pimelic anhydride; subericanhydride; 2,2-dimethylsuccinic anhydride; 3,3-dimethylglutaricanhydride; 2,2-dimethylglutaric anhydride; dodecenylsuccinic anhydride;nadic methyl anhydride; and HET anhydride and said hydroxy(meth)acrylate compound is selected from the group consisting of2-hydroxyethyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate;2-hydroxybutyl (meth)acrylate; 2-hydroxy 3-phenyloxypropyl(meth)acrylate; 1,4-butanediol mono(meth)acrylate; 4-hydroxycyclohexyl(meth)acrylate; 1,6-hexanediol mono(meth)acrylate; neopentylglycolmono(meth)acrylate; trimethylolpropane di(meth)acrylate;trimethylolethane di(meth)acrylate; pentaerythritol tri(meth)acrylate;dipentaerythritol penta(meth)acrylate; octenyl succinic anhydride, andhydroxy functional (meth)acrylates represented by the following formula,

wherein R₁ is a hydrogen atom or a methyl group and n is an integer from1 to
 5. 37. The laminated flexible packaging material of claim 35,wherein said anhydride comprises succinic anhydride.
 38. The laminatedflexible packaging material of claim 35, wherein said anhydridecomprises phthalic anhydride.
 39. The laminated flexible packagingmaterial of claim 35, wherein said anhydride comprises alkenesubstituted succinic anhydride.
 40. The laminated flexible packagingmaterial of claim 39, wherein said anhydride comprises dodecenylanhydride.
 41. The laminated flexible packaging material of claim 39,wherein said anhydride comprises octenyl succinic anhydride.
 42. Thelaminate flexible packaging material of claim 35, wherein said hydroxy(meth)acrylate compound is 2-hydroxyethyl acrylate.
 43. The laminatedflexible packaging of claim 35, wherein said hydroxy (meth)acrylatecompound is 2-hydroxyethyl methacrylate.
 44. The laminated flexiblepackaging material of claim 35, wherein the organic titanate comprisesthe reaction product of a least one titanate with one to four alkylgroups and a half-ester compound formed by the reaction of a hydroxy(meth)acrylate compound with an organic anhydride.
 45. The laminatedflexible packaging material of claim 44, wherein the organic titanate isformed by pre-reacting the alkyl titanate with the half-ester compoundthat is formed by the reaction of a hydroxy (meth)acrylate compound withan organic anhydride.
 46. The laminated flexible packaging material ofclaim 44, wherein the organic titanate is formed in-situ with blendingof other laminating adhesive components.
 47. The laminated flexiblepackaging material of claim 35, wherein the organic titanate is formedfrom tetraisopropyl titanate.
 48. The laminated flexible packagingmaterial of claim 35, wherein the organic titanate is formed fromtriethanol amine titanate.
 49. The laminated flexible packaging materialof claim 35, wherein the organic titanate is present at a level of about1 to about 15% by weight of the adhesive composition.
 50. The laminatedflexible packaging material of claim 35, further comprising less than50% by weight of at least one mono or multi-functional (meth)acrylatemonomer or oligomer.
 51. The laminated flexible packaging material ofclaim 35, wherein the adhesive is formulated to be curable by electronbeam radiation through at least one layer of flexible packagingmaterial.
 52. The laminated flexible packaging material of claim 35,further comprising about 0.2 to about 15% of a photoinitiator, whereinthe adhesive is curable by ultraviolet radiation.
 53. The laminatedflexible packaging material of claim 35, wherein the layers of flexiblepackaging materials are selected from the group consisting of polyolefinbase films, polyester based films, polyamide based films, copolymerfilms, coextruded polymer films, metalized films, coated films, printedfilms, paper, and aluminum foil.
 54. The laminated flexible packagingmaterial of claim 35, wherein the adhesive layer is present at a weightof about 0.5 to about 2.5 pounds per 3000 square feet of flexiblepackaging material.
 55. The laminated flexible packaging material ofclaim 35, comprising three of more layers of flexible packagingmaterials that are bonded by at least two layers of saidradiation-curable laminating adhesive.
 56. The laminated flexiblepackaging material of claim 35, comprising three or more layers offlexible packaging materials that are bonded by one layer of saidradiation-curable laminating adhesive and at least one layer of anon-radiation-curable adhesive.
 57. A laminated flexible packagingmaterial of claim 35, wherein said carboxylic acid monomer has a numberaverage molecular weight of from about 100 to about
 3000. 58. Alaminated flexible packaging material of claim 35, wherein saidcarboxylic acid monomer has a number average molecular weight of fromabout 150 to about
 2000. 59. A laminated flexible packaging material ofclaim 35, wherein said carboxylic acid monomer has a number averagemolecular weight of from about 200 to about
 1500. 60. A laminatedflexible packaging material of claim 35, wherein at least one layer offlexible packaging material comprises at least one polymeric materialselected from the group consisting of polyolefins, polyesters,polyamides, and polystyrenes.
 61. A laminated flexible packagingmaterial of claim 35, wherein at least one layer of flexible packagingmaterial comprises a polyolefin based film.
 62. A laminated flexiblepackaging material of claim 35, wherein at least one layer of flexiblepackaging material comprises a polyethylene or polypropylene based film.63. A laminated flexible packaging material of claim 35, wherein atleast one layer of flexible packaging material comprises a polyolefinbased film is coated with another material.
 64. A laminated flexiblepackaging material of claim 63, wherein said another material comprisespolyvinylidene chloride, acrylic, or a metal.
 65. A laminated flexiblepackaging material of claim 35, wherein at least one layer of flexiblepackaging material comprises a polyolefin based film comprising apolyolefin blended with another material.
 66. A laminated flexiblepackaging material of claim 35, wherein at least one layer of flexiblepackaging material comprises a polyolefin based film comprising apolyolefin copolymerized with another material.
 67. A laminated flexiblepackaging material of claim 66, wherein said another material comprisesvinylacetate or vinyl alcohol.
 68. A laminated flexible packagingmaterial of claim 35, wherein at least one layer of flexible packagingmaterial comprises a polyolefin based film comprises a polyolefincoextruded with another material.
 69. A laminated flexible packagingmaterial of claim 35, wherein at least one layer of flexible packagingmaterial comprises a polyolefin comprising at least one selected fromthe group consisting of homopolymers or copolymers of ethylene,butylene, propylene, hexene, and octene, copolymers of ethylene withvinyl acetate, vinyl alcohol, ethyl acrylate, or acrylic acid, andcoextruded films containing a polyolefin.
 70. A laminated flexiblepackaging material of claim 35, wherein at least one layer of flexiblepackaging material comprises polypropylene.
 71. A laminated flexiblepackaging material of claim 35, wherein said radiation-curablelaminating adhesive contains a polymeric photoinitiator.
 72. A laminatedflexible packaging material of claim 35, wherein at least one layer offlexible packaging material has a thickness of from about 0.1 mil toabout 5 mils.
 73. A laminated flexible packaging material of claim 35,wherein at least one layer of flexible packaging material issubstantially clear and contains printed material on an inside surfacethereof.
 74. A laminated flexible package suitable for containing apharmaceutical, beverage or food grade product comprising a laminatedflexible package material comprising at least two layers of flexiblepackaging materials bonded together by a radiation-cured laminatingadhesive, wherein the radiation-curable laminating adhesive comprises:a. at least 50% of one or more carboxylic acid functional (meth)acrylatemonomers which are the half-ester formed by the reaction of ahydroxy(meth)acrylate compound with an organic anhydride, and b. about0.1 to about 20% of an organic titanate compound, the flexible packagingdefining an interior space suitable for containing a liquid or solidfood product or a pharmaceutical product.
 75. A packaged food productwhich has been packaged using a laminated flexible packaging materialcomprising at least two layers of flexible packaging materials bondedtogether by a radiation-cured laminating adhesive, wherein theradiation-curable laminating adhesive comprises: a. at least 50% of oneor more carboxylic acid functional (meth)acrylate monomers which are thehalf-ester formed by the reaction of a hydroxy(meth)acrylate compoundwith an organic anhydride, and b. about 0.1 to about 20% of an organictitanate compound.
 76. A packaged pharmaceutical product which has beenpackaged using a laminated flexible packaging material comprising atleast two layers of flexible packaging materials bonded together by aradiation-cured laminating adhesive, wherein the radiation-curablelaminating adhesive comprises: a. at least 50% of one or more carboxylicacid functional (meth)acrylate monomers which are the half-ester formedby the reaction of a hydroxy(meth)acrylate compound with an organicanhydride, and b. about 0.1 to about 20% of an organic titanatecompound.
 77. A packaged beverage product which has been packaged usinga laminated flexible packaging material comprising at least two layersof flexible packaging materials bonded together by a radiation-curedlaminating adhesive, wherein the radiation-curable laminating adhesivecomprises: a. at least 50% of one or more carboxylic acid functional(meth)acrylate monomers which are the half-ester formed by the reactionof a hydroxy(meth)acrylate compound with an organic anhydride, and b.about 0.1 to about 20% of an organic titanate compound.
 78. A processfor bonding two or more layers of flexible packaging materialscomprising: applying one or more layers of liquid radiation-curablelaminating adhesives comprising: a. at least 50% of one or morecarboxylic acid functional (meth)acrylate monomers which are thehalf-ester formed by the reaction of a hydroxy(meth)acrylate compoundwith an organic anhydride, and b. 0.1 to 20% of an organic titanatecompound to at least one layer of flexible packaging material on amoving web followed by bringing another layer of flexible packagingmaterial into contact with the wet adhesive and then curing the adhesiveby exposure to UV or electron beam irradiation.
 79. A process of claim78, wherein the layers of flexible packaging materials are selected forma group consisting of polyolefin based films, polyester based films,polyamide based films, copolymer films, coextruded polymer films,metalized films, coated films, printed films, paper, and/or aluminumfoil.
 80. A process of claim 78, wherein the adhesive layers are appliedat weighs ranging from 0.5 to 2.5 pounds per 3000 square foot ofpackaging material.
 81. A process of claim 78, wherein theradiation-curable laminating adhesives are cured by electron beamirradiation originating from at least one side of the moving multi-layerlaminated web.
 82. A process of claim 81, wherein electron beamirradiation has accelerating voltage of about 60 to 250 KV applied at adosage of about 0.5 to 6.0 Mrads.
 83. A process of claim 81, whereinelectron beam irradiation has an accelerating voltage of 70 to 170 KVapplied a dosage of 1.0 to 4.0 Mrads.
 84. A process of claim 81, whereinthe adhesive also contains 0.2 to 15% by weight of a photoinitiator andis cured by UV irradiation though at least one layer of flexiblepackaging material that is substantially clear to allow transmission ofUV light.
 85. A process of claim 84, wherein the UV light has awavelength ranging from 200 to 450 nanometers.
 86. A process of claim78, wherein two layers of flexible packaging materials are bonded by onelayer of said radiation-curable adhesive.
 87. A process of claim 78,wherein three of more layer of flexible packaging materials are bondedby at least two layers of said radiation-curable laminating adhesive.88. A process of claim 78, wherein at least two layers of saidradiation-curable laminating adhesives are simultaneously cured by oneelectron beam generating unit.
 89. A process of claim 78, where three ormore layers of flexible packaging materials are bonded by one layer ofsaid radiation-curable laminating adhesive and at least one layer of anon-radiation-curable adhesive.
 90. A process of claim 89, wherein thelayer or radiation-curable laminating adhesive and the layer onnon-radiation-curable laminating adhesive are applied and cured in onecontinuous web process.
 91. A process of claim 78, wherein the bondingof the layers of flexible packaging materials occurs in-line withprinting of graphics on the package.
 92. A process of claim 78, whereinthe bonding of the layers of flexible packaging materials occursoff-line with printing of graphics on the package.
 93. A process forbonding two or more layers of flexible packaging materials to form alaminated flexible packaging material comprising: applying one or morelayers of liquid radiation-curable laminating adhesives comprising: a.at least 50% of one or more carboxylic acid functional (meth)acrylatemonomers which are the half-ester formed by the reaction of ahydroxy(meth)acrylate compound with an organic anhydride, and b. 0.1 to20% of an organic titanate compound to at least one layer of flexiblepackaging material on a moving web followed by bringing another layer offlexible packaging material into contact with the wet adhesive and thencuring the adhesive by exposure to UV or electron beam irradiation toform a laminated flexible packaging material, wherein the resultingcured adhesive has low migration of adhesive components into a packageformed from the laminated flexible packaging material making it suitablefor pharmaceutical and food grade products.
 94. A radiation-curablelaminating adhesive comprising: a. at least 50% by weight of one or morecarboxylic acid functional (meth)acrylate monomers which are thehalf-ester formed by the reaction of a hydroxy(meth)acrylate compoundwith an organic anhydride, and b. 0.1 to 20% by weight of an organiczirconate compound.
 95. A radiation-curable laminating adhesivecomprising: a. at least 50% by weight of one or more carboxylic acidfunctional (meth)acrylate monomers which are the half-ester formed bythe reaction of a hydroxy(meth)acrylate compound with an organicanhydride, and b. 0.1 to 20% by weight of at least one selected from thegroup consisting of organic zirconates, organic aluminates, and/ororganic zinc.
 96. A laminated flexible package material comprising atleast two layers of flexible packaging materials bonded together by aradiation-cured laminating adhesive, wherein the radiation-curablelaminating adhesive comprises: a. at least 50% of one or more carboxylicacid functional (meth)acrylate monomers which are the half-ester formedby the reaction of a hydroxy(meth)acrylate compound with an organicanhydride, and b. about 0.1 to about 20% of an organic zirconatecompound.
 97. A laminated flexible package material comprising at leasttwo layers of flexible packaging materials bonded together by aradiation-cured laminating adhesive, wherein the radiation-curablelaminating adhesive comprises: a. at least 50% of one or more carboxylicacid functional (meth)acrylate monomers which are the half-ester formedby the reaction of a hydroxy(meth)acrylate compound with an organicanhydride, and b. about 0.1 to about 20% of at least one selected fromthe group consisting of organic zirconates, organic aluminates, andorganic zinc.